London, May 9 : Using a miniature detector, scientists would be able to pick out magnetic rocks on Mars that might harbour telltale signs of ancient life.
The instrument, designed by Sam Kim of NASA's Jet Propulsion Laboratory in Pasadena, California, US, scans rock samples to find these magnetic signatures. It is about twice as long as a shoebox, weighs about 2 kilograms and requires just 5 watts of power. ccording to a report in New Scientist, the instrument would be able to select rocks that contain a magnetic compound - magnetite - that is also produced by bacteria on Earth. The rocks could then be brought back to Earth for closer examination.
Though efforts to find signs of life on Mars have focused on organic molecules, but Kim wants to look for crystals of magnetite like those made by terrestrial bacteria.
"Because it's just a mineral, it has a better chance of survival over billions of years," Kim told New Scientist.
"It looks like a very interesting idea - to look for signatures of these crystals on Mars directly," said John Miller, a physics professor at the University of Houston in Texas, US, who has worked on ways of finding life on Mars.
Some terrestrial bacteria make magnetite so they can orient themselves with the Earth's magnetic field and move along it in search of the most favourable conditions.
Mars doesn't have a global magnetic field now, but evidence suggests it once did.
"If that's the case, then there could have been some impetus for organisms of that nature to evolve - if indeed life took hold," said Miller.
Other microbes produce magnetite as a byproduct of using iron in their metabolism.
So if life took hold on Mars, it might have taken advantage of the abundance of iron on Mars, whose distinctive red hue comes from iron oxide, according to Miller.
Researchers have previously used microscopes to examine magnetite in Mars rocks. With the new detector, "we don't have to study particle after particle under the microscope", said Kim.
The detector has not been assigned to any specific Mars missions, but according to Kim, it could offer a good "preliminary sample selection tool" for a future Mars sample return mission.